Infrastructure Engineering - Theses
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ItemEvaporation from an agricultural catchment: a field and theoretical study of evaporation( 1983-05)This is a field and theoretical study of the evaporation component of the hydrology of an agricultural catchment. The aim of the study was to improve the evaporation section of the Australian Representative Basis Model, ARBM. ARBM is a physically based computer model of catchment hydrology. It was developed for use in conjunction with the representative Basins Project. The catchment selected for this study was the Warrambine Creek Representative Basin, No. 2.15. A major part of the study was the development of equipment to directly measure evaporation in the field. Two sets of equipment were developed. One system was based on the energy balance method of evaporation measurement. The other system was based on the eddy correlation method. In its final form, the energy balance equipment proved most satisfactory. At the study site over 100 days of complete data was collected. However this data was discontinuous due to instrument and data recording faults. The data collected was used in the testing of various components of the evaporation model. A detailed analysis was undertaken to estimate the likely errors in the computer values of evaporation. This analysis showed that little error could be expected when evaporation was measured over a wet surface. For a dry surface, the analysis predicted that erratic results could occur. This prediction was confirmed with experimental evidence. The development of the eddy correlation system was less successful. This occurred because of the late start to this section of the work and because of the innovative nature of the equipment which was developed. A microprocessor system was designed to replace the eddy correlation analogue computers. This system offers many advantages over conventional equipment. Unfortunately it was only developed to the laboratory testing stage. Also an infrared hygrometer was designed. This too was only tested in the laboratory. Although no field measurements of evaporation were made with this equipment, additional theory and insight into this method was obtained. The performance of any hydrological model depends on the reliability and representativeness of its input data. This data is supplied by a Bureau of Meteorology climate station situated only 3 km from the study site. The location of the climate station appears to be non-representative of the catchment in general. Thus climatic data from the two sites was compared. Little difference was noted in dry bulb temperature and rainfall data. Wet bulb depressions were slightly different. A poor correlation of pan evaporation was found. It was also found that the global radiation data collected at the climate station was worthless due to an instrument fault. The evaporation model of ARBM was examined in detail. In particular, the parameter known as potential evaporation, PE, was examined from first principles. It was found that PE is poorly defined. PE was re-defined and prediction formulae were derived. These formulae were used in a new PE model for ARBM. The model which predicts the diurnal variation of evaporation was examined and found to be satisfactory. Particular improvements to the equipment and topics of further study were recommended.
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ItemA new refined approach to the formulation of the earthquake-resistant design regulations for torsionally coupled multistorey buildings( 1989)This thesis presents a detailed parametric study of the elastic earthquake response of torsionally coupled single and multi storey buildings using a probabilistic approach. The aim is to validate the findings of previous deterministic studies, to assess the empirical design procedures stipulated by the current provisions of building codes, and to critically appraise the alternative design recommendations made by the earlier deterministic studies. The structural models are idealised by a discrete parameter prismatic shear beam model which is representative of low to moderately high rise frame-type buildings. The earthquake horizontal ground motion is modeled as a Gaussian, zero mean, stationary random process that is fully characterised by a probabilistic ground acceleration power spectrum. The first and second order statistical parameters defining such a spectrum are derived from an ensemble of 68 actual earthquake motions recorded in the west coast of the U.S.A. A new procedure called the Intensity Correlated Probabilistic Power Spectrum Method (ICPPSM) is developed. This procedure uses the standard random vibration and extreme value theories, and the new concept of the intensity correlated probabilistic power spectrum to compute the mean peak structural responses. Based on the numerical results obtained from the probabilistic approach, a more rational three-step formulation to the codified seismic torsional provisions is proposed to allow for the coupling effects in the design of multi storey buildings.
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ItemGeotechnical studies for machine tunnelling( 1983)An exhaustive program of measurement of the mechanical properties and drillability test indices of rocks from Australian tunnels and mines was followed by extensive statistical analyses, to find correlations between the various rock properties and drillability tests. Significant correlations were found between Young's modulus and point load strength, Young's modulus and shear strength, and shear strength and unconfined compressive strength. Several other relationships between properties which had been previously published by other authors were confirmed but modified, with less significant correlations. Several laboratory drillability tests, which are small-scale simulations of full-size field drilling and tunnelling machines, were shown to give results which were well correlated with groups of rock mechanical properties. In most cases, however, there were no simple correlations, which could unequivocally explain the mode of rock failure. Rock failure in response to a drill or cutter, whether full size or laboratory scale, is evidently a complex and subtle inter-relationship of several factors. The performance of a full-face tunnel boring machine was monitored, and correlated with the results of mechanical property and drillability tests performed upon rock samples taken from the walls of the tunnel. Significant correlations were found which can be used as equations to predict the advance rate of a tunnel boring machine and the rate of wear of the cutters. The significant independent variables include drillability test indices, the machine propel or thrust force, and physical properties of the rocks. Tensile or compressive strengths were not found to be significant factors in predicting tunnelling machine performance.
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ItemRock mass characterization and its application to assessment of unsupported underground openings( 1980)The research study centres on the stability assessment of unsupported, sub-level open stopes located within the silver-lead-zinc orebodies at the Mount Isa Mine in Queensland, Australia. A systematic approach is adopted for characterization of rock masses and a statistically-based model is formulated to account for local variability in geological structure. Investigations suggest that the degree of fracture clustering observed in some masses may not have resulted from a random process. A zonal model is proposed for spatial distribution of these weakness planes. The general validity of the assumed model with respect to the dolomitic shales at the mine is confirmed by computer simulation of fracture distributions within three-dimensional blocks. The computer program used in the simulation process has been developed as part of the project. Mechanical properties of the mass are derived on the basis of the statistical model for geological structure and various published rock mass classification systems. A computer program is used to expedite these analyses. Alternate approaches for derivation of properties are mentioned. Several techniques are employed to assess the significance of statistically variable material properties on stability of the stapes. These include rock mass classifications, two-dimensional finite elements with elasto-plastic behaviour and sequential excavation, and the probability of failure analysis. Limitations of each technique are discussed. Some consideration is given to broadly reviewing past mining experience within stapes at the mine. Results of analyses demonstrate that a greater depth of understanding and appreciation of rock mass behaviour may be gained from modes with locally variable material properties. A reasonable degree of correlation is achieved between model and prototype response.
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ItemSimulation of hay-making systems( 1986)In southern Australia, fodder is conserved mainly as hay, and pasture is the common raw material. This hay-making process is complex and, unlike other harvesting operations which are virtually instantaneous, involves a series of sequential operations with three or more different machines. It also involves a number of major and minor management decisions in a highly variable weather regime and with continuously changing crop conditions. A simulation model has been developed to evaluate alternative hay-making systems and management policies in terms of the digestible dry matter (DDM) yield of hay and of the harvesting time. The main simulation is based on a series of sub-models associated with pasture growth, weather forecasts, management, hay-drying and hay losses. Some of these models are based on the available literature and others have been developed by the author. Field-drying experiments with unconditioned and conditioned pasture were conducted to develop the hay drying model which also includes the effect of dew and rain. A method was developed to make an assessment of three-day weather forecasts for scheduling hay-making operations. Simulation experiments were carried out by using 16 years of historical weather data from Laverton, Victoria. Management factors such as weather prospects after cutting, maximum cut crop allowed in the swath and maturity at the start of season were found to affect the DDM yield and harvesting time. To achieve a significant increase in DDM yield of hay, either an improvement in the accuracy of weather forecasting is necessary or the drying time in the field must be reduced by applying a treatment such as conditioning of the crop at the time of cutting. The major limitation of the present simulation model is the lack of data. Research is needed to refine the loss parameters due to environmental factors and mechanical operations on which the DDM yield is based. A number of other promising research areas also are outlined to extend the use of the present model and make improvements to it.